Project Summary The proposed research will challenge the standard approach to lumbar interbody fusions (LIFs) by utilizing medical imaging, finite-element (FE) models and emerging materials to guide novel device design. These fusions are performed annually on 500,000 patients who suffer from degenerative disc disease, instability, and scoliosis. This proposal offers an innovative, multi-disciplinary approach to studying LIFs. Conventional CT will be correlated and utilized to predict local strength and modulus values across the endplates. These data will also be used to create patient-specific, FE models with the matching material properties. FE simulations will be used to evaluate the complex biomechanics of the spine for a wide variety of cages/rod designs, materials, and configurations. Furthermore, simulations will yield valuable information regarding the stress distribution across the endplates as well as overall construct stiffness as a function of bone formation and fusion. Lastly, poly(para-phenylenes) (PPPs) are a new class of aromatic polymers with strength and modulus values higher than poly(ether-ether-ketone) (PEEK). PPPs have superior manufacturability compared to current cage materials and will be made into porous devices. The porosity of the device will be spatially tailored to match the properties of the implant across the endplates, while also promoting osteointegration of bone. Our hypothesis is that a porous interbody fusion cage would reduce complications (subsidence and adjacent-level disease) and improve clinical outcomes by (1) spatially tailoring the modulus of the implant to the endplate, (2) more evenly distributing stresses across the entire endplate, (3) lowering the overall construct stiffness value, and (4) allowing for osteointegration of bone into the implant. If successful, the proposed research would shift the paradigm for how LIF cages and constructs are designed as well as lower rates of subsidence, implant failures, and adjacent-level disease. The proposed team consists of an inter- disciplinary group with backgrounds in clinical surgery, mechanical and biomedical engineering, and materials science.